Exemptions to scope of the standards provided for in 26.0504 are as follows:

(a) New buildings and/or modifications there or whose peak design rate of energy usage is less than 1 watt per square foot of floor area for all purposes; and

(b) Those buildings which are not mechanically cooled;

(c) Requirements for heated buildings;

(d) Any historical building or property eligible for, nominated to, or entered on the national register of historical places pursuant to the National Historic Preservation Act of 1966, PL 89-665, or the American Samoa register of historic places; The lighting efficiency standards shall apply to all public buildings with over 10,000 square feet of floor space whose rate of energy usage is greater than 2.5 watts per square foot.